Authors:

J.W. Berkery(Columbia U)

S.A. Sabbagh(Columbia U)

Y.S. Park(Columbia U)

J.H. Ahn(Columbia U)

Y. Jiang(Columbia U)

J.D. Riquezes(Columbia U)

S.P. Gerhardt(PPPL)

C.E. Myers(PPPL)

The Disruption Event Characterization and Forecasting (DECAF) code, being
developed to meet the challenging goal of high reliability disruption
prediction in tokamaks, automates data analysis to determine chains of
events that lead to disruptions and to forecast their evolution. The
relative timing of magnetohydrodynamic modes and other events including
plasma vertical displacement, loss of boundary control, proximity to density
limits, reduction of safety factor, and mismatch of the measured and desired
plasma current are considered. NSTX/-U databases are examined with analysis
expanding to DIII-D, KSTAR, and TCV. Characterization of tearing modes has
determined mode bifurcation frequency and locking points. In an NSTX
database exhibiting unstable resistive wall modes (RWM), the RWM event and
loss of boundary control event were found in 100{\%}, and the vertical
displacement event in over 90{\%} of cases. A reduced kinetic RWM stability
physics model [1] is evaluated to determine the proximity of discharges to
marginal stability. The model shows high success as a disruption predictor
(greater than 85{\%}) with relatively low false positive rate. [1] J.W.
Berkery, et al., Phys. Plasmas \textbf{24} (2017) 506103. $^{\mathrm{\ast
}}$Supported by US DOE Contracts DE-FG02-99ER54524, DE-AC02-09CH11466, and
DE-SC0016614.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2017.DPP.CP11.93